3. Pollen seasons assessment
The start and end dates of pollen season were March 5 and June 7, respectively and the pollination duration was 94 days in 1998. Meanwhile, the the start and end dates were February 15 and July 5, respectively and the pollen season duration was 140 days in 2019 (Fig. 2). Total concentration and peak concentration of pollens were increased gradually for the last 22 years (Fig. 3). These data implied the start and end date of tree pollination in the future at Seoul metropolitan area was predicted to widen the interval as the start day and the end date will be February 9th and June 24th 2027, by using ARIMA-11 analysis. (Table 3). Accumulated temperature is critically correlated to pollination. Herein, the mean accumulated temperature at start day was 182.14±52.02ºC during the pollination (Table 2). Both variables are critical correlated to pollination. Annual changes in the pollen season showed the start date became earlier and the end date later from 1998 to 2019 in Seoul metropolitan area.
4. Relationship of the sensitization rates to pollens with the pollen seasons duration and meteorological observation .
Regression model for each tree demonstrated that sensitization rate to oak, hazel, pine, birch, alder, and willow was increased 0.28%, 0.28%, 0.23%, 0.25%, 0.28%, and 0.25% from year to year during 22 years respectively. The duration of the pollen seasons was positively correlated with the sensitization rate to oak, hazel, pine, birch, alder, and willow (r= 0.79, 0.81, 0.85, 0.79, 0.80, and 0.70, respectively). The sensitization rate to pollens was positively correlated with the accumulated temperature also positively correlated (correlation coefficient: Oak 0.71; hazel 0.66; pine; 0.53, birch 0.69; alder 0.53; willow 0.64) (Table 2). The other meteorological data were not shown the significant relation to sensitization rate with pollen seasons duration.